Fixes #1969: Enhance ElDoc integration

To improve the ElDoc experience for Evil mode users, this commit adds
the following commands to the ElDoc system:
- evil-delete-*
- evil-insert-*
- evil-append-*

This fixes the issue where ElDoc help disappears from the minibuffer
when using Evil mode, after executing certain Evil commands
such as deleting words or characters.

Author: jamescherti

evil-integration.el

@@ -454,8 +454,24 @@ Based on `evil-enclose-ace-jump-for-motion'."
 
 ;;; ElDoc
 (eval-after-load 'eldoc
+  ;; The following prevents ElDoc help from disappearing in the minibuffer when
+  ;; executing certain Evil commands in Emacs, such as
+  ;; `evil-delete-back-to-indentation', `evil-delete-backward-word',
+  ;; `evil-insert', `evil-insert-line', `evil-append', `evil-append-line'...
   '(when (fboundp 'eldoc-add-command-completions)
-     (eldoc-add-command-completions "evil-window-")))
+     (eldoc-add-command-completions "evil-window-")
+
+     ;; Add evil-delete commands to ElDoc to display help while deleting using:
+     ;; - evil-delete-backward-word (C-w)
+     ;; - evil-delete-back-to-indentation (C-u)
+     ;; - evil-delete-backward-char-and-join (C-h)
+     ;; - And other evil-delete-* commands.
+     (eldoc-add-command-completions "evil-delete-")
+
+     ;; Add insert and append commands to ElDoc to display help after switching
+     ;; to insert mode.
+     (eldoc-add-command-completions "evil-insert-")
+     (eldoc-add-command-completions "evil-append-")))
 
 ;;; XRef
 (eval-after-load 'xref